Question

(a) How many significant figures are there in the following: 

(i) 0.0026 

(ii) 6.022 × 10¹³ 

(b) Calculate the number of carbon atoms is 34.20 g of C₆H₁₂O₆.

Answer 1

(a) (i) 0.0026 = 2.6 × 10^–3

It has two significant figures.

(ii) 6.022 × 10¹³

It has four significant figures.

(b) Number of particles in a mole = 6.023 × 10²³

Molecular mass of C₆H₁₂O₆ = 180

Number of carbon atoms = 6

\(\therefore\) 180 g of C₆H₁₂O₆ contains

= 6 × 6.023 × 10²³ carbon atoms

\(\frac{6\times6.023\times10^{23}\times34.20}{180}\)

= 6.866 × 10²³ carbon atoms